Industrial embedded systems requiring real-time control are being widely introduced, such as factory automation (FA) systems and broadcast video systems. Since these industrial embedded systems require real-time control between embedded CPUs (Central Processing Unit) that are geographically dispersed, real-time communication is realized using dedicated communication protocols and dedicated field buses.
However, along with lower costs and wider bandwidth for Ethernet (registered trademark), which is widely used in communication networks, systems realizing communication networks in industrial embedded systems by Ethernet (registered trademark) are becoming common.
“Communication delay guarantee” for realizing real-time control is cited as a requirement of a network in an industrial embedded system. In order to provide a guarantee with regard to communication delay in Ethernet (registered trademark), an End-to-End bandwidth reservation system is described in Patent Literatures (PTLs) 1 and 2.
In the systems described in Patent Literatures 1 and 2, bandwidth reservation is carried out by determining transmission rate for each node pair so as to maximize the utilization rate of network bandwidth, and setting the determined transmission rate in a rate control unit corresponding to a destination node.
[PTL 1]
Japanese Patent Kokai Publication No. JP-H07-245626A
[PTL 2]
Japanese Patent Kokai Publication No. JP2006-074600A